[mythtv-users] anyone h.264 transcoding? want to share your magic?

Brian J. Murrell brian at interlinx.bc.ca
Sun Feb 15 20:50:16 UTC 2015


Hi,

So, I've decided that I want to post-recording transcode to h.264 with
ffmpeg.  I wonder if anyone has any reasonable SD resolution ffpmeg
command lines for such that they have found to be reasonable and produce
files that mythtv will play.

My first two samples went OK.  In my third sample, I managed to create a
file that mythtv chokes on about 14 mins into a 60 minute recording.
Mplayer plays it just fine.  When hitting the fail point, mythavtest
would stop playing, bring up the recording finished menu and emit the
following error repeated many times:

2015-02-15 14:58:21.336504 E  decoding error
			eno: Unknown error 541478725 (541478725)

I of course tried rebuilding the seek table with "mythcommflag --rebuild
--file ..." but that just made mythtv believe the file was only ~14
minutes long.  mythcommflag produced the following output:

2015-02-15 15:00:39.748064 C  mythcommflag version: fixes/0.27 [v0.27.4-4-gb305eb5] www.mythtv.org
2015-02-15 15:00:39.748123 C  Qt version: compile: 4.8.1, runtime: 4.8.1
MythTV Commercial Flagger, building seek table for:
    The West Block
Rebuild started at Sun Feb 15 15:00:40 2015
No I-frames found, rewinding...
Rebuild completed at Sun Feb 15 15:02:17 2015
2015-02-15 15:02:17.379780 E  decoding error
			eno: Unknown error 541478725 (541478725)

I'm guessing it hit the same error and figured the file was only as long
as it was able to read.

So, I could continue mucking around with ffmpeg flags, but if somebody
has already blazed this trail, I'd sure appreciate the fruits of your
labour.

FWIW, this is what I am using currently:

ffmpeg -i /storage2/3093_20150215155900.mpg -y -map 0:0 -map 0:1 -er 4 -acodec libvo_aacenc -ac 2 -ab 128k -ar 44100 -deinterlace -vf crop=720:360:0:60 -vcodec libx264 -crf 18 -level 30 -g 90 -async 2 -threads 0 -v 0 /storage2/3093_20150215155900.mkv

if somebody cares to critique/suggest alternate flags/switches.  ffmpeg version is:

ffmpeg version 0.8.16-4:0.8.16-0ubuntu0.12.04.1, Copyright (c) 2000-2014 the Libav developers
  built on Sep 16 2014 18:35:14 with gcc 4.6.3

Cheers,
b.

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